Connector



Dec. 5, 1950 BERGAN 2,533,161

' CONNECTOR Filed May 26, 1949 INVENTOR. MARTIN D. BERGAN M fi ATTORNEY.

Patented Dec. 5, 1950 CONNECTOR Martin D. Bergan, Westfield, N. .L, assignor to The Thomas & Betts 00., Elizabeth, N. J., a corporation of New Jersey Application May 26, 1949, Serial No. 95,400

1 Claim. (Cl. 285'6.5)

This invention relates to a new and useful connectorhaving a novel mode of operation affording increased convenience when installing it in service position, providing for longer life, and enhancing its reuse.

The principle of the invention lends itself to the improved manufacture of fittings for making electrical connections, the joining of rod members, and for effecting various forms of splicing and coupling operations, etc, where the fitting for these kindred purposes embodies a simple and known form of screw-actuated clamping strap.

However, the example of the invention, as selected for disclosure and treatment herein, comprises a new connector useful for assembling raceways which enclose and insulate electrical- 'wiring installations; that is, for connecting BX cable, as well as conduit of various types, with electrical outlet and raceway boxes in general. Consequently, the example of the invention presented herein, as to its principle, relates to a non-conductive connector but is claimed in respect to all its adaptations and in any environment of its new operating means for more efliciently handling the old tvpe screw-actuated clamping strap above mentioned.

Among other uses for the invention, its outright simplicity finds immediate application in solving a long existing problem in electricalraceway connectors, specifically the screwactuated clamp strap type (a so known as squeeze type) cable connectors for flexiblemetallic conduit as well as BX cable. Such connectors are employed for assembling conduits which enclose the electrical conductors of power and lighting circuits. Raceway connectors of the species improved upon herein are well known in the art.

The prior art contains raceway connectors for the commonly known BX cable and flexiblemetallic conduit, both of which have spirally-- armored conductors ordinarily called cable in the trade. Thus, for convenience, the term cable herein may as well be used generically to mean both types of spiral-armor, if not indeed electrical conductors as such, since the invention finds utility not only in improving non-conductive raceway fittings but may also be employed in the electrical connector field as Well.

, Prior cable connectors of the species in question-all alike in principle but difiering somewhat in structural form-have a screw-actuated clamping or squeezing strap which fastens the cable (spiral-armor) in the tubular body of the 2 connector. In general, the old type of clamping screw turns with considerable friction and wear because the movable clamping strap varies its angle of engagement with the head of the screw. Thus the plane of the swingable clamping strap, intersecting the axis of the rotating screw, constantly changes its angle of intersection. A side force is thus exerted by the old type clamping strap at an angle against its screw, thereby reducing the efficiency of the screw and presenting the problem which this invention seeks to solve.

In further explanation of the problem herein, it is next pointed out that the above recited "side forceacting on the screw at an angle to its axistends to tilt the screw off of its normal axis of rotation. Such abnormal misalignment (or the angu ar force tending to cause same) generates friction in the rotating screwthreads, thus requiring excess effort of a workman for turning the screw, and causing wear of the screw-threads, thereby reducing the reusable life of the connector.

In many instances, the present-day cable connector is difficult to install-for in forcing its rotation by a screwdriver, the threads may be crossed or worn or chipped. Thus damaged, the connector may fail to maintain its required degree of clamping pressure on the cable, may have a short life, and if removed from the installation is not fit for reuse. Actually, any screw, which is not guided on its normal axis of rotation, is twice subjected to wear and tear not only of its threads but also the threads of the member which it engagesonce when screwed inwardly under pressure and again when removing the screw.

While the foregoing explanation of the problem is brief, and does not outline all the causes and effects arising out of the geometrical variation of the forces involved, the matter is believed clear to those conversant with this branch of the prior art, especially so after further study of the teachings herein and a comparison of this new connector with representative types known to the art. Accordingly, the invention may now be more fully considered, its purpose, and how it solves the problem.

The purpose of the invention is to provide a novel operating means for screw-actuated clamping strap devices which resolves all angular force components along a single straight line, that is, along the axis of screw rotation, thereby freeing the screw of side force-introducing no force at an angle to its axisthus permitting the screw to perform its dual motion (combined rotation and longitudinal travel) exactly along the axis not only of its own threads but also the axis of the screw-threaded hole in which it is operatively mounted.

Thus stated, one will appreciate by study and comparison that the accomp ishment of the foregoing purposeinhibits all forces tending to tilt or displace the screw off the two axes, that of its own threads and that of the threads which it operatively engages. Accordingly, the screw .of the new operating means herein is so improved by reason of its new operating environment that it rotates and longitudinallyitraveis in and out of clamping pressure with a minimum "of friction and wear.

It follows, therefore, that a giventorque .otthe screwdriver, during installation, is fully utilized in driving the screw home. In other w'ords, a percentage of the active torque is not dissipated wearing or fracturing thescrew-threads. .Such improvements in function :make. for convenience of installation. Also, the screw has longerlife andis adapted for numerous reuses,-by reason of its freedom from wear and'tear, as-will be ap preciated 'by considering one important structural example of theinvention illustrated herein. .The accompanying drawings withwdescription and-claim explain the invention as-preferred and embodied at this time .fora an understanding of the problems. sought to be :solved. Since :the

with "its clamping strap and novel operating :means therefor carried-on therear '(outer) end of the tubular body; in wide open position, .:for receiving a maximum .size cable, or large size electrical :conductor, or vother .membery. adapted to beconnected with rand'by this fitting.

":Fig. shows .atransverse section on .theJine i2:-.2, across the-rear end'of the connectonlook- :ing toward theifront (inner) end, with itsiclarnping screw :partly withdrawn, in order toillustrate more 'cearly theiscrew-threaded hole at the'lower right hand side of the view, an important consideration herein.

t Fig. .3fShOWS a top view of the connector clamped 011 a piece of 'BX cable or a piece of fiexiblemetalic conduit (spiral-armor) of the maximum size adapted to be received by the fitting.

Fig. =4. shows a transverse section on the line 4-4, thus being .arear end'vi'ew looking toward the front end of the connector, with the maxi- :mum size piece of cable clamped therein.

Fig. '5 also is a transverse section similar 'to Fig. 4, except showing a minimum size cable secured in the connector.

Figs. 4 and 5 are comparison views which demvonstratetherange of sizesof cable, conduit, elec- 'trical conductors, or other members, which are adapted to be connected with or by this fitting. Thus, a maximum size cable is shown in Figs. .3 and 4, while a minimum size thereof .is seen inFig. 5. It will be understood that in practice -ally screw-threaded.

there are a number of intermediate sizes of cables, etc., which may be used with this connector.

Figs. 2 and 3 include dot-and-dash lines A, etc., indicating the axes of certain parts of the new connector, in aid of explaining the concept of invention herein.

Referring further to the drawings for a more detailed description of'th'e invention, it will be understood by those conversant with the art that cable connectors of the type in question comprise a tubular body, the front end H] of which is usu- This end portion IB is adapted to be inserted into a raceway opening (such-as a conduit .box hole), with an annular shoulder :.l:i:..abutting the outside surface of the box, and=the tubular body secured in the box by a.lock nut tightened onto the threaded end I0. Such conventional raceway parts, as the box and nut, :etc., are well understood and omitted from the drawings for clarity.

":An-..:ea-r,- t2 is carried '01'1'dihe:':lB&1Il1d. of :the tubular :body, with :a screw-threaded hole: i3 provided through the ear outside the body cir- -cumference.- In this example ofuconstruction, the ear is integral with the tubular: body at. the circumference of the .latter. .T-he -ear is comparatively rigid in order to maintain the-screwthreaded hole 13, and .henceits. axis, in a position fixed (as :near as 1 may be possible) saga-inst 2 displacement -when under' clamping "strain. Thus the :axis of the threadedihole l3rstands :perpem dicular to .the-zaxis 0f the tubular body.

An arcuate clamping strap I4 is also carried on thereareend of the: tubular body "it .as,';for example, by forming -the:inner.-end .of. the'st-rap integrally with .the tbody .:on:.the "circumference thereof; This "strap .is separated from the rear end of the body by anarrow sclearanceslot :15 in "orderzthat thestrapmayibencl and :swing inward otthe body-circumference. One or more weakening notches 1.6 :may .be'provided in :the :arcuate :strapmea-r: its integral 2end,. as :a means for linducing'the strap to bend :near its inner *end.(see Fig. 5:)vwhen-its outersfreeuend is drawn'toward the :ear. :l2ior clampingracable C, 'or otherlike ;member, within the connector bodyil U.

The outer free rrendof the clamping strap 14 is provided with a'screweclearance aperture 1 Bout- .side themircumference of :theitubular body and ini-axialaalignment; that "is, vcoaxially with the screw-threaded hole 1530f the rigid ear 12. "It is observed :that the arcua'te 'clamping strap i4 is formed from a long segment of the circumference o'f thc tubular bos y, "while :theear J2 comprises a short or stub segment thereof; "Thus therlon'ger'reach of thestrap makes it bendable toward the-ear, the latter being short to impart stiitnessthereto' 'so asyto remain "stationary against pulling force of the strap.

(Incidentally, the tubularbody it is usually formed of malleable stock as, for example, sheet steel or the .like' (when manufacturing connec- .ItOls; for raceway :use and other non-conductive utility), thu's-providing for inward bending or flexure of the "clamping strap M a't'its inner-integral end portion where it is notched at it to facilitate bending motion. The action of the strap is shown by the comparison views (Figs. 4 and '5) demonstrating the considerable range in sizes of *spiral armor cables C to which the strap is adapted for clamping movement toward the rigidand stationaryear I2.

The foregoing description and parts are largely conventional and constitute oneexemplary environment or setting for the invention, asnext described herein, by which a new combination is attained, characterized by a novel mode of operation, and resulting in functional improvements beneficial to the art.

A headed-clamping screw is operatively 'mounted in the arcuate clamping strap l4 and rigid ear l2. Thus a common screw has its threaded shank I9 rotatably mounted through the enlarged screw-clearance aperture I8 of the outer free end of the movable clamping strap I4,

and its shank extremity is threadedly engaged withinthe screw-threaded hole i3 of the rigid ear-l2. A screw head 20 on the end of the threaded shank I9 is somewhat larger than the clearance aperture l8 and thus bears against provided at 2| on the outer free end of the clamping strap I4, symmetrically on both sides of the screw-clearance aperture I8, and against 'which the screw head 20 rides under pressure during tightening operation. This character istic feature comprises a lengthwise ridge or longitudinal-crest which is outwardly ovalled or ridge-crowned by a smooth semi-circular frictionless surface formed outside of the circumference of the tubular body and outward or away from the rigid ear l2. It is noted that the crest-formation of the bearing-crown 2| and the screw-threaded ear l2 are spaced from each other outside the circumference of the tubular body and that the axes of the screw-clearance aperture l8 and the screw-threaded hole l3 are in alignment. These geometrical aspects of the new connector operating means are best emphasized by next referring to the three axis lines A, etc., on the drawings.

In Fig. 3, the longitudinal axis of the tubular body It) is indicated by a dot-and-dash line BA, while the longitudinal bearing-crown 2| has its axis along a dot-and-dash line CA. Thus, it is seen that the body axis BA and the crown axis CA are parallel which is important concerning the new operating means herein for the clamping strap M. Then in Fig. 2, the axis of the threaded shank N3 of the clamping screw is indicated by a dot-and-dash line 3A, this axis line also indicating the common center lines or axes of the enlarged screw-clearance aperture l8, as well as the screw-threaded hole l3. Thus all three last-named portions (the screw IS, the aperture l8, and the hole l3) have a common axis 3A which is perpendicular to the tubular body axis BA as well as the bearing-crown axis CA.

According to the foregoing description and study of the accompanying drawings, it is observed that the inner flat surface of the screw head 2|] rotatably engages the oval-lengthwise crest of the bearing-crown 2| with minimumarea pressure engagement when drawing the resisting clamping strap I4 from its outer position (Fig. 2 or 4) to its inner position (Fig. 5). The minimum-area of pressure engagement, between the plane of the screw head 20 and the bearing-crown 2|, afiords easy and near frictionless operation of the clamping screw during its dual motion of rotation and longitudinal travel in relation to the screw-threaded hole |3. This is accomplished by reason of the fact that the novel bearing-crown 2| 'makes for constant tangential engagement between the screw head 2|! and the clamping strap 14 for all changing positions of the latter throughout its range of movement.

The bearing-crown 'zloeing equally or symmetrically disposed on both sides of three axes 3A in common (Fig. 2), also acting at all times near or substantially on said axis, and in tangent relation to the screw head 2|J-functions to equalize the angular reaction and the bending resistance of the clamping strap I'd, as it is drawn inwardly, and causes said strap to resolve its angular component and apply its force in a 0011-: stant direction against the screw head, to-wit, coaxially thereof along said axis 3A. Of importance is the fact that the bearing-crown 2| acts to resolve the changing angular reaction of the clamping. strap M into a single force component which is uniformly and constantly co'-. axial with the three common axes 3A, thereby avoiding any exertion of an angular force against the threaded shank IQ of the clamping screw.

Such operation is free of all tilting force or side stress and permits the threaded shank I9 freely to rotate and travelin or out, along the common axis 3A (of the screw shank IS, the ole rance aperture l8, and the threaded hole 3), hence uniformly and evenly along said axis of the threaded hole with a minimum of friction therein. Accordingly, there exists a minimum of wear and damage to both sets of screw-threads l3 and |9 of the connector.

By comparing the several positions which the bearing-crown 2| assumes in relation to the center of the screw-head 25 (using the axis line 3A as a reference), throughout the range of operation of the clamping strap is (Figs. 2, 4 and 5. it will be observed that the crest of said bearingcrown creeps slightly from one side of the axis line to the other side thereof, but that it equalizes on each side and maintains pressure engagement tangent to the plane of the fiat-bearing area 20 of the screw head.

Now it is observed how closely the bearing crown axis CA hugs the tri-axes 3A throughout the cable-sizes range of operation. For the large size cable C (Figs. 3 and 4), it is seen that the axis CA of the clamping strap bearing-crown 2| intersects the axis 3A; hence the resistance of the strap i4 is exerted coaxially of the screwthreaded hole [3, which is an ideal operating condition achieved by the invention. And for small size cable, the crown axis CA holds so closely to the tri-axes 3A that side or tilting force on the screw shank i9 is negligible.

The foregoing new mode of operation provides an easy turning screw head and shank, makes for convenience in installing the connector, better adapts it to a range of cable sizes, particularly for small size cable (Fig. 5), does not require excess screwdriver torque to tighten the clamping strap M, preserves the screw threads l3 and I9, increases the life of the connector, and en hances its overall utility for reuse if and when removed from an original installation.

This disclosure explains the principles of the invention and the best mode contemplated in applying such principles, so as to distinguish the invention from others; and there is particularly pointed out and distinctly claimed the part, improvement or combination, which constitutes the invention or discovery, as understood by a comparison thereof with the prior art.

The invention is presented to fill a need for rams-n 1 7 ea;anewi andrusefnlaconnectcr. Nariousumodificiitions in construction, *fmode :of, operation, zuse xandmethod, may :and gotten: do "000111".t0 others,

aespecially so -:after :acquaintance with an invention. Accordingly, it is to be understocdithat this i disclosure :is exemplary of .the principleszherein sand embraces equivalent aconstructions.

. What is claimed ,is:

.In a connector of-the type having :a tubular .roodycadapted to :receive :a cable, with, a rigid --:ear

..ca-rriedont-the tubularbody and provided with a screw-:threaded hole, a.. clamping strapmaving its .inner end carried'nn the body and its outerend tree --for:- movement toward the rigid ear, the outer, free :{endheing provided with :a .screw- .ciearancexaperture which is -:c0axia1 with .-,the

rscrewathrea'ded. hole and aoperating .-means, .1f01*.drawing :the iclampingystrap towaidathe rigid .ear, including atheaded-clamping screw. havinga --,threade d shank-:mountedthrough -the "screwclearance aperture and ,threadedlyengaged'witm 4ini-the eoaxialiyzscitewathreaded: hole .of a the *rigid ear; and also including and .beingcharacterized --:by:a. bearing-*crowmin the: form of a longitudinalicrestpmyidedon:thenuter f-ree end-ofvthe clamp- '1 strap, with said longitudinal-crestdisposed "outward from the rigid -ear,-and on bothsidesnf the screw-clearance aperture; as wellas along van iaxis parallei with. the of :thetubular "foriall positionsiassumedhy said screw headaazid said clamping strap, .zthroughout their range" to! operaticnywhether gripping large: size or.;smaJ1 size- .cable, by which the threaded tshank also rotates with a:.minim11m=of friction, aszwell ias ffr'ee'do-m :from wear, within the screw threaded hole.

' .iMARTIN D.2BERGAN.

"REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name :Date

Re. 20,873 Fuliman Oct. '4, "-1938 2,272,939 Funk Feb; 10,1942 12,315,685 .Bowers .Apr. '6, 31.943 

